Factors influencing the long-term development of sediment dynamics in proglacial channels in the European Alps

Abstract

The system of proglacial streams in the Alps has experienced significant changes since the end of the Little Ice Age. Previous studies showed different patterns of aggradation and degradation in proglacial channels over time. This leads to the question of which factors determine the sediment dynamics in the channels and on their floodplains in the long term with ongoing glacier melting. Possible influencing variables are the distance of a channel section to the recent glacier tongue and the percentage of glaciation in the catchment area. Moreover, we suppose an influence of local topographic characteristics such as the slope gradient and the width or confinement of the channel. In addition to these factors, there is also the question of whether large individual events overlay a trend of aggradation or degradation.In order to analyse the long-term sediment dynamics in channels and the factors influencing it, we used numerous digital elevation models (DEMs) covering several decades and different streams within three main catchments (Kaunertal and Horlachtal in Tyrol and Martelltal in South Tyrol). The DEMs were generated from aerial images dating back until 1953. From the 2000s on, airborne LiDAR datasets and DEMs based on drone images were available. This data basis enables a comparative investigation and the identification of local topographic influences.